Jump to content

18 Monocerotis

From Wikipedia, the free encyclopedia
18 Monocerotis
Location of 18 Monocerotis (circled red)
Observation data
Epoch J2000      Equinox J2000
Constellation Monoceros
Right ascension 06h 47m 51.64752s[1]
Declination 2° 24′ 43.7737″[1]
Apparent magnitude (V) 4.47[2]
Characteristics
Spectral type K0+IIIaBa0.2[3]
U−B color index +1.04[2]
B−V color index +1.11[2]
Astrometry
Radial velocity (Rv)+11.29[4] km/s
Proper motion (μ) RA: -16.898[1] mas/yr
Dec.: -16.229[1] mas/yr
Parallax (π)8.0947 ± 0.2385 mas[1]
Distance400 ± 10 ly
(124 ± 4 pc)
Absolute magnitude (MV)-0.78[5]
Orbit[6][7]
Primary18 Monocerotis A
Companion18 Monocerotis B
Period (P)1760.9±1.9 d
Semi-major axis (a)6.63 mas
Eccentricity (e)0.40±0.04
Inclination (i)96.25°
Longitude of the node (Ω)47.63°
Periastron epoch (T)2441942.5
Argument of periastron (ω)
(secondary)
172±6°
Details
18 Mon A
Radius26.95+1.56
−0.81
[1] R
Luminosity311.2±10.5[1] L
Surface gravity (log g)2.59[8] cgs
Temperature4,750[9] K
Metallicity [Fe/H]-0.03[5] dex
Rotational velocity (v sin i)< 2.0[10] km/s
Other designations
18 Mon, BD+02°1397, FK5 258, GC 8892, HD 49293, HIP 32578, HR 2506, SAO 114428[11]
Database references
SIMBADdata

18 Monocerotis is a binary star system located about halfway from Orion's Belt to Procyon,[6] in the equatorial constellation of Monoceros.[11] It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.47,[2] and is positioned around 370[1] light years away from the Sun based on parallax. The system is receding from the Earth with a heliocentric radial velocity of +11 km/s.[4]

It is reported as a single-lined spectroscopic binary with an orbital period of 1,760.9 days (4.8 years) and an eccentricity of 0.4.[6] The visible component is an aging K-type giant star with a stellar classification of K0+IIIaBa0.2,[3] showing a slight overabundance of barium. The spectrum displays strong violet lines of CN.[6] With the supply of hydrogen at its core exhausted, this star has expanded to 27[1] times the radius of the Sun. It is radiating 311[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,750 K.[9]

References

[edit]
  1. ^ a b c d e f g h i j Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. ^ a b c d Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
  3. ^ a b Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H. 5050. Bibcode:1995yCat.5050....0H.
  4. ^ a b Famaey, B.; Jorissen, A.; Luri, X.; Mayor, M.; Udry, S.; Dejonghe, H.; Turon, C. (2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data". Astronomy & Astrophysics. 430: 165–186. arXiv:astro-ph/0409579. Bibcode:2005A&A...430..165F. doi:10.1051/0004-6361:20041272. S2CID 17804304.
  5. ^ a b Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644. Vizier catalog entry
  6. ^ a b c d Griffin, R. F. (1984). "Spectroscopic binary orbits from photoelectric radial velocities. Paper 59: 18 Monocerotis". The Observatory. 104: 267. Bibcode:1984Obs...104..267G.
  7. ^ ESA (1997). "The Hipparcos and Tycho Catalogues". VizieR On-line Data Catalog. Bibcode:1997yCat.1239....0E.
  8. ^ Soubiran, Caroline; Le Campion, Jean-François; Brouillet, Nathalie; Chemin, Laurent (2016). "The PASTEL catalogue: 2016 version". Astronomy & Astrophysics. 591: A118. arXiv:1605.07384. Bibcode:2016A&A...591A.118S. doi:10.1051/0004-6361/201628497. S2CID 119258214.
  9. ^ a b Gontcharov, G. A. (2009). "Red giant clump in the Tycho-2 catalogue". Astronomy Letters. 34 (11): 785–796. arXiv:1607.00619. Bibcode:2008AstL...34..785G. doi:10.1134/S1063773708110078. S2CID 73524157. Vizier catalog entry
  10. ^ De Medeiros, J. R.; Mayor, M. (1999). "A catalog of rotational and radial velocities for evolved stars". Astronomy and Astrophysics Supplement Series. 139 (3): 433. arXiv:astro-ph/0608248. Bibcode:1999A&AS..139..433D. doi:10.1051/aas:1999401. Vizier catalog entry
  11. ^ a b "18 Mon". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-05-30.